I'm interested in the Lamy CP1 Tri Pen, which is a multipen that comes with three pen types - black ballpoint (M 21), pencil (M 41), and orange marker (M 55).
Is it possible to swap out the pencil and orange marker with additional M 21 (or non-Lamy ballpoint) refills? I would prefer a mix of three ballpoint colours.
The How To Refill video from Lamy doesn't provide many clues as the guide shows a sketch rather than the actual pen.
I also found a similar question on Drop, but the response was inconclusive.